Final answer:
Social context is extremely important in gerontology because it shapes how people define core concepts such as age, old age, and normative life course.
Step-by-step explanation:
The option that is extremely important in gerontology because it shapes how people define core concepts such as age, old age, and normative life course is Option a: Social context. Social context refers to the social environment and conditions that influence individuals and their development. In the study of gerontology, understanding the social context is crucial as it helps to explain how societal factors impact the aging process and the experiences of older adults.